Cup



April 7, 1964 w. R. PRICE ETAL CUP Original Filed May 9, 1957fi-ZVEHZUFS Warren 8. Price 'A/exanaer Sfan/cyfiaasfan W, 5% VW UnitedStates Patent 3,128,029 CUP Warren R. Price, Skokie, and AlexanderStanley Houston, Chicago, 111., assignors to St. Regis Paper Company, acorporation of New York Original application May 9, 1957, Ser- No.658,155, now Patent No. 2,942,301, dated June 28, 1960. Divided and thisapplication Dec. 3, 1959, Ser. No. 2,318

1 Claim. (Cl. 229-15) The instant invention relates to receptacles, andmore particularly, to a unique receptacle structure formed of foamedpolystyrene.

The present application is a division of our application Serial No.658,155, filed May 9, 1957, now Patent No. 2,942,301.

The formation of foamed resins is known generally and, for example, asindicated in US. Patent No. 2,023,204, issued to Munters and Tandbergand US. Patent No. 2,450,436, issued to Mclntire, the manufacture offoamed polystyrene is well known. The instant invention, however,resides in a particular structure formed of highly vesiculatedlightweight polystyrene composed of closed cells, in which the structureis in the form of a receptacle, having been formed from a flat sheet byhot-drawing.

The resulting receptacle has unique properties and is economicallymanufactured so that it is competitive with paper cups or receptaclesand has distinct advantages thereover in its physical properties. Forexample, the instant material is very lightweight and, although it ishot-drawn or formed from a flat sheet into the receptacle shape, theinsulating properties thereof are not lost. Instead, the instantreceptacle has such distinctly superior heat insulative properties thatthe cup may be retained in the hand, even though boiling water is pouredinto the cup. The instant material is, of course, moisture-proof. Thecells therein are closed cells, so that moisture permeation is preventedand the advantages of insulation are retained. The instant material isalso grease-resistant. The instant material is also distinctly superiorto paper cups in that it does not impart a taste to beverages(particularly alcoholic beverages) retained therein. In contrast, theusual wax-coated paper cup is not sufficiently resistant to alcoholicbeverages to prevent imparting taste thereto. Although the foamedpolystyrene sheet material from which the instant receptacle is formedis very thin and lightweight, the instant cup is quite strong, easily asstrong as paper cups, and is self-supporting under the weight of theliquid therein.

It is, therefore, an important object of the instant invention toprovide an improved receptacle.

It is another object of the instant invention to provide a superior cupfor retaining liquids, which is highly resistant to liquid permeation.

Still another object of the instant invention is to provide an improvedcup formed of grease-proof, moistureproof, lightweight, heat insulativefoamed polysytrene.

Other and further objects, features and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed disclosure thereof and the drawings attached heretoand made a part hereof.

On the drawings:

FIGURE 1 is a view in perspective of a receptacle embodying the instantinvention;

FIGURE 2 is an enlarged sectional elevational view of the receptacle ofFIGURE 1; and

FIGURE 3 is a more greatly enlarged sectional elevational detail viewtaken substantially along the line III-III of FIGURE 2.

As shown on the drawings:

In FIGURES 1 and 2, there is shown a receptacle or cup indicatedgenerally by the reference numeral 10. Actually, the cup 10 has thegeneral shape of a flower pot and, although it will be appreciated thata number of other receptacle shapes may be employed in the practice ofthe instant invention, it will be appreciated that the cup 10 hascertain advantageous structural features. For example, an outwardlyturned flange or lip 11 is formed along the top periphery of the cup 10and an annular ridge 12 is formed in the upstanding cup walls Wintermediate the bottom 13 and the top lip 11. The top lip 11 and theintermediate ridge 12 give added strength to the cup 10 and facilitatethe manual handling thereof.

As will be seen from FIGURE 2, the walls W of the cup 10 are taperedgenerally from the top lip 11 to the reduced diameter 'of the bottom 13.Actually there is an upper wall portion W-1 which tapers inwardly fromthe top lip 11 to the ridge 12, whereat the diameter of the walls W isreduced; and the lower wall portion W-2 also tapers inwardly from theannular ridge 12 to the bottom 13.

As indicated in FIGURE 3, the cup 10 is formed of a highly vesiculatedlightweight mass of polystyrene (indicated in section) composed ofnumerous closed cells C (indicated as circles in. FIGURE 3).

In general, the cup 10 is formed by initially extruding foamedpolystyrene into a flat sheet of substantially uniform thickness in therange of 0.020 to 0.070 inch, followed by hot-drawing this flat sheetinto the instant cup between suitable dies which are heated at atemperature (of about C.) suflicient to effect deformation of the flatsheet. The deformation effected is permanent, because the material isheated to its deformation temperature between the dies. This requiresthe application of pressure, of course, in order to effect suchdeformation, but the small cells C which may be crushed or eliminatedduring the hot pressing operation tend to appear substantially entirelyas they were in the original flat sheet as soon as the pressure isremoved. The pressure is removed While the material is still hot. Inthis way the cellular character of the material is not lost during thissubsequent forming step. The advantages of lightweight and heatinsulation are retained, while the additional advantages of strength inthe receptacle-shaped device are gained. The inherent resilience in thematerial is retained to a desirable extent.

The resulting cupis unique in a number of respects. In appearance, ithas a generally fibrous character, which is due to the extrusion formingoperation of the initial flat sheet, but which is not lost by thesubsequent hotdeformation. In effect, the hot-deformation subtractsnothing from the original advantageous features of the fiat sheet, butadds the desired structure of the receptacle. The instant receptacle isunique in that it can be held in the hand while very hot water is pouredinto the receptacle, and the insulating effect is so good that one isbarely able to feel a slight warming of the outside walls of the cupwhen hot water is poured into the cup.

In the practice of the instant invention the initially formed flat sheetis preferably formed by extrusion through a circular orifice followed byslitting of the resulting tubular material so as to form the flat sheet.The extrusion is preferably carried out by a so-called blow extrusionprocess. The general features of this type of procedure are shown in theaforementioned McIntire US. Patent No. 2,450,436. In a continuousoperation, of course, the materials are fed into one end of the extruderwith a suitable gas generating material, which may be in the form of amaterial which is normally a gas or it may be in the form of a materialwhich decomposes at the temperature which the material reaches justbefore departing from the extruder. If the mateso the material is heatedin the extruder to effect a sufficient softening thereof and thedissolving of the methyl chloride therein effects the formation of agel, which is extruded from the machine. The extrusion thereof releasesthe pressure on the polystyrene mass thus permitting the methyl chloride(or other gas-forming material) retained or dissolved therein toseparate from the viscous solid mass and form numerous small gas cells.The formation of the gas requires heat of vaporiza tion which effectscooling of the polystyrene (which could not be cooled easily in otherways because of the poor heat conductivity).

For example, the polystyrene material which may be formed by carryingout the instant process may have a specific gravity as low as 0.04.Sheets of such material are available commercially in thicknessesranging from 0.020 inch to 0.070 inch (and specific gravity of 0.04),and such sheets may be hot-formed into a receptacle such as the cup 10.

As a specific example, a sheet of foamed polystyrene having a thicknessof 0.030 inch and a specific gravity.

of 0.04 is laid over a positive mold member having the general shape ofthe interior of the cup 10, and a negative mold member is pressed downover the sheet at 15 p.s.i. gauge pressure, while the sheet is heated to150 C. The mold is opened while the sheet is still hot. The resultingcup 10 is found to have excellent strength and resilience. It hasretained its original specific gravity of 0.04 and its grease-proof andwater-proof properties. It is also a heat insulator whose thermalconductivity k (in Btu/square foot/hour/ F. per foot) is found to be inthe order of 0.25.

Comparable results are obtained using the same operating conditions on asheet of extruded polystyrene having a thickness of 0.05 inch.

It will be understood that modifications and variations may be efiectedwithout departing from the spirit and scope of the novel concepts of thepresent invention.

We claim as our invention:

A cup consisting of a seamless integral piece of highly vesiculatedpolystyrene having closed cells therein; said cup having continuousside, base, and corner Wall portions of uniform thickness throughout;said thickness being in the range of from 0.020 to 0.070 inch; and saidpolystyrene having a specific gravity on the order of 0.04; the highlyvesiculated character of the polystyrene being uniform throughout thesaid side, base, and corner wall portions of said cup.

References Cited in the file of this patent UNITED STATES PATENTS2,415,323 Wilcox Feb. 4, 1947 2,484,608 Cheyney et al Oct. 11, 19492,606,586 Hill Aug. 12, 1952 2,614,727 Robinson Oct. 21, 1952 2,722,719Altstadter Nov. 8, 1955 2,737,503 Sprague et a1. Mar. 6, 1956 2,770,406Lane Nov. 13, 1956 2,805,790 Smucker Sept. 20, 1957 2,917,217 SissonDec. 15, 1959

